This invention relates to a welding power supply system which may be used for shielded metal arc welding, plasma arc welding, and inert gas arc welding, and has particular application to inert gas arc welding using nonconsumable electrodes, such as tungsten, commonly referred to as a tungsten inert gas (TIG) welding used in the welding of aluminum, aluminum alloys and similar metals.
Square wave welding power supplies are described in various prior art patents including U.S. Pat. Nos. 3,068,352; 3,330,933; 3,382,345; 3,300,683; 3,598,954 and 3,999,034.
Many of the prior art welding power supplies include two reactor controlled power sources to provide welding current of opposite polarities to an arc circuit. If high arc voltages are required, then additional power sources must be connected in parallel, and the result is four power supplies, the total weight of which can be as much as 5,000 pounds. Another disadvantage when using reactor controlled power sources is that one or the other of the power sources is short circuited during the period when it is not connected to the arc to allow that power source to be under constant regulation, an obviously inefficient arrangement.